This view of the twilight sky and Martian horizon taken by NASA's Curiosity Mars rover includes Earth as the brightest point of light in the night sky. Earth is a little left of center in the image, and our moon is just below Earth.

This frame from an animation from NASA's Mars rover Curiosity shows the rover drilling into rock target 'Cumberland.' The drilling was performed during the 279th Martian day, or sol, of the Curiosity's work on Mars (May 19, 2013).

This image from the Mars Hand Lens Imager on NASA's Mars rover Curiosity shows the patch of rock cleaned by the first use of the rover's Dust Removal Tool (DRT). The tool is a motorized, wire-bristle brush on the turret at the end of the rover's arm.

The two bodies in this portion of an evening-sky view by NASA's Mars rover Curiosity are Earth and Earth's moon. The rover's Mast Camera (Mastcam) imaged them in the twilight sky of Curiosity's 529th Martian day, or sol (Jan. 31, 2014).

This mosaic of images from the Mast Camera (Mastcam) on NASA's Mars rover Curiosity shows Mount Sharp in a white-balanced color adjustment that makes the sky look overly blue but shows the terrain as if under Earth-like lighting.

This set of images illustrates how the science filters of the Mast Camera (Mastcam) on NASA's Mars rover Curiosity can be used to investigate aspects of the composition and mineralogy of materials on Mars.

This set of images illustrates how the science filters of the Mast Camera (Mastcam) on NASA's Mars rover Curiosity can be used to investigate aspects of the composition and mineralogy of materials on Mars.

This image of terrain inside Mars' Gale Crater and the calibration target for Mastcam on NASA's Mars rover Curiosity illustrate how false color can be used to make differences more evident in the materials in the scene.

These three versions of the same image taken by the Mast Camera (Mastcam) on NASA's Mars rover Curiosity illustrate different choices that scientists can make in presenting the colors recorded by the camera.

The color cameras on NASA's Mars rover Curiosity, including the pair that make up the rover's Mastcam instrument, use the same type of Bayer pattern RGB filter as found in typical commercial color cameras.

This set of images illustrates the twin cameras of the Mastcam instrument on NASA's Curiosity Mars rover (upper left), the Mastcam calibration target (lower center), and the locations of the cameras and target on the rover.

On this image of the broken rock called 'Tintina,' color coding maps the amount of mineral hydration indicated by a ratio of near-infrared reflectance intensities measured by the Mastcam on NASA's Mars rover Curiosity.

On this image of the rock target 'Knorr,' color coding maps the amount of mineral hydration indicated by a ratio of near-infrared reflectance intensities measured by the Mastcam on NASA's Mars rover Curiosity.

Indication of Hydration in Veins and Nodules of 'Knorr' in 'Yellowknife Bay'

At different locations on the surface of the same rock, scientists can use the Mast Camera (Mastcam) on NASA's Mars rover Curiosity to measure the amount of reflected light at a series of different wavelengths.

This graphic presents results from APXS onboard NASA's rover Curiosity, with the comparisons simplified across diverse elements by dividing the amount of each element measured in the rocks by the amount of the same element in a local soil.

The gray area in center of this image is where the Dust Removal Tool on NASA's Mars rover Curiosity brushed a rock target called 'Wernecke.' The brushing revealed dark nodules and white veins crisscrossing the light gray rock.

The Dynamic Albedo of Neutrons (DAN) instrument on NASA's Mars rover Curiosity detects even very small amounts of water in the ground beneath the rover, primarily water bound into the crystal structure of hydrated minerals.

Variation in Water Content in Martian Subsurface Along Curiosity's Traverse

This set of graphs shows variation in the amount and the depth of water detected beneath NASA's Mars rover Curiosity by use of the rover's Dynamic Albedo of Neutrons (DAN) instrument at different points the rover has driven.

The Dynamic Albedo of Neutrons (DAN) instrument on NASA's Mars rover Curiosity took measurement on a rock outcrop (Spot 39) and on loose soil (Spot 40) within the 'Yellowknife Bay' area of Mars' Gale Crater.

This view of Curiosity's left-front and left-center wheels and of marks made by wheels on the ground in the 'Yellowknife Bay' area comes from one of six cameras used on Mars for the first time more than six months after the rover landed.